Paint spray control system



Dec. 5, 1967 R. F. WIGGINS PAINT SPRAY CONTROL SYSTEM 3 Sheets-Sheet 1Filed March 11, 1965 INVENTOR. RICHARD F. WIGGINS 777 L o nmsvs Dec. 5,1967 3 Sheets-Sheet 2 Filed March 11, 1965 S m R6 mm m v m -w A H m R MY B m v U l D W N R W I D ATTORNE S Dec. 5, 1967 R. F. WIGGINS PAINTSPRAY CONTROL SYSTEM Filed March 11, 1965 3 Sheets-Sheet 5 SPRAY RANGESWITCH FIG. 6

FIG. 7

SPRAY RANGE INVENTOR. RICHARD F. WIGGINS ATTO RNE$SV United StatesPatent 3,356,061 PAINT SPRAY CONTROL SYSTEM Richard F. Wiggins,Fair-field, C0nn., assignor to The Gyr mat Corporation, Stratford,Conn., a corporation of Connecticut Filed Mar. 11, 1965, Ser. No.439,017 1 Claim. (Cl. 118-2) ABSTRACT OF THE DISCLOSURE This inventionis directed to a mechanical. memory unit in combination with a timercontrol, which combination functions to control the sequential sprayingof a plurality of conveyed articles which may have their leading andtrailing edges non-uniformly spaced. The memory unit detects, in theabsolute sense, the presence or absence of an article to be sprayed andaccordingly remotely controls the starting of a spray gun while thetimer control determines the precise instant of starting the spray andthe duration of the spray based upon the relationship of the leading andtrailing edges to the spray guns.

spray gun, only in the presence of a conveyed article .and nototherwise. In the case of electrostatic spraying,

it may also be important to control spray application accurately tocontrol wrap-around of the spray material.

Accordingly, for optimum operating efiiciency and maximum safety, theoperation of the spray gun itself should be directly controlled by therelation or orientation therewith of the article to be coated in orderthat the spray nozzle be actuated only at times when the article iswithin desired range of the nozzle.

Detection of an article in the immediate presence of the spray gunpresents little problem when a gun is manually controlled andselectively actuated by an operator using his own vision to detect anarticle passing a spray station. However, when the spray gun is to beautomatically operated and controlled, the substitution of mechanical orelectronic article detectors in the immediate presence or in the generalvicinity of the spray gun has not been found to be especially reliable,since the detcctors, themselves, easily tend to become contaminated,fouled, or otherwise inoperative through the build-up and accumulationof spray coatings thereon.

In accordance with the present invention, reliable control of a spraycoating apparatus, having one or more spray guns, by aconveyor-supported article may be achieved with a new and improved,remotely situated, conveyor actuated spray programmer. Specifically, thenew programmer includes a rotatable memory wheel, which is synchronouslyindexed or otherwise synchronized with the travel of a continuouslymoving conveyor having pendants thereon, and a plurality of regularlyspaced memory pins carried by the memory wheel. The memory pins areselectively projectable by a solenoid into an .article detected positionfrom a normal, article undetected position in accordance with thepresence or absence, respectively, of an article on a conveyor pendant(either by detection of the article itself or its supporting pendant) asit passes a mechanical or electronic detection device, such as a limitswitch, photo-cell, or the like, remotely positioned with respect to thespray gun.

Associated with the memory wheel and supported on spaced radial sprayswitch arms are impulse switches which, in response to actuation by thememory pins, start the individual spray guns at predetermined delayedinstants and for predetermined durations determined by the specific sizeof the articles being sprayed and the conveyor speed. In accordance withan important aspect of the invention, the spaced relation of thedetection means with respect to the spray apparatus and the spacedrelation of the memory wheel solenoid with respect to the spray switcharms are proportionally prearranged in such a manner that the spray gunsare operated only when an article is detected and passes within itsspray range and at no other time. Accordingly, whenever there has beenan omission of a suspended article from the conveyor, deliberate orotherwise, the spray apparatus will not be activated when the emptyportion of the conveyor passes it, since the memory pin associated withthat portion of the conveyor will not have been projected by thesolenoid.

It will thus be appreciated that the control system of the invention isessentially in the nature of an analog of a portion of the spray systemitself, in which that portion of the continuously moving conveyorbetween the detection point and the spray point is analogicallyrepresented by the memory wheel, an article on the conveyor isanalogically represented by a projected memory pin, and the individualspray guns are analogically represented by the spray switch arms.Moreover, it will be understood that the new spray programmer providesconveyor actuated, positive, sensitive, and contamination-free controlof any number of spray guns in a reliable, simplified, and mostefiicient manner.

For a more complete and better understanding of the invention, referenceshould be made to the following detailed description taken inconjunction with the accompanying drawings, in which:

FIG. 1 is a perspective representation of a paint spray system includinga new and improved spray control programmer embodying the principles ofthe present invention;

FIG. 2 is a front elevational view of the memory wheel of the new andimproved spray programmer;

FIG. 3 is a cross-sectional view of the memory wheel taken along line3-3 of FIG. 2;

FIG. 4 is an enlarged, cross-sectional view of a memory pin taken alongline 44 of FIG. 2;

FIG. 5 is a schematic representation of an article to be sprayedapproaching the spray range of a spray gun;

FIG. 6 is a schematic representation of an article to be sprayedentering the spray range of a spray gun; and

FIG. 7 is a schematic representation of an elongate article to besprayed supported from a pair of adjacent conveyor pendants.

Referring to FIG. 1, the spray programmer of the present invention isgenerally indicated by reference numeral 10 and is adapted for use withan endless conveyor 11 having any suitable number of regularly orotherwise spaced pendants 12 thereon, each of which is adapted toreceive an article hanger 13 supporting an article 8. As-

.sociated with the conveyor, which is continuously driven clockwise byan appropriate motor drive 9, are spray guns 14 and 15.

As an important aspect of the invention, initiation of the timedoperating sequence for the spray guns 14 and 15 is accomplishedextrinsically of the immediate vicinity .or atmosphere of the spray gunsand of the spray booth means. Projectable memory pins 19 areequiangularly arrayed at predetermined spacings about the memory wheel17, and spaced spray switches 20, 21 are adapted to cooperate withprojected ones of the memory pins.

In accordance with the invention, a detection limit switch 22 is locatedremotely of and free from contamination by the spray guns 14, in thepath of the hangers 13 to be reliably actuable thereby. The detectionswitch 22, which in certain applications may be a photo-cell, proximityswitch or the like, is appropriately connected to a solenoid 23 havingan armature adapted to project a memory pin into an active position torepresent analogically each hanger 13 and hence each article detected bythe switch 22.

In the illustrated arrangement, an indexing limit switch 63 isappropriately connected to the indexing drive 18 and is locatedimmediately adjacent the path of spaced conveyor pendants 12, if theyare regularly spaced, or other elements of the conveyor or its drivefrom which a regular indexing signal can be derived. The indexing drive18 is periodically actuable by the switch 63 in accordance withadvancement of the conveyor to cause the clockwise indexing of thememory wheel a single pin spacing to correspond with a predeterminedincrement of conveyor advance.

More specifically and with reference to FIG. 2, the memory wheel 17includes a predetermined number of memory pins 19, equal to or greaterthan the number of conveyor pendants 12 between the detecting andspraying stations. These pins are equiangularly supported in holes 19aspaced circumferentially of the wheel. As shown best in FIG. 3, thememory wheel 17 is mounted for rotation about a shaft 26 supported by anappropriate frame 25, which shaft mounts a substantially circularholding plate 27 in a spaced relation to the memory plate. In accordancewith the invention, each of the memory pins 19 includes an outer switchactuating portion 29 and an inner control portion 30 (FIG. 4) and ismovable axially of the memory wheel 17 between limit positions imposedby the engagement of two annular shoulder stops 31, 32 with the surfacesof the memory wheel.

As shown in FIGS. 2 and 3, the outermost edge portions 28 of the holdingplate 27, in accordance with the invention, extend to a point betweenthe control portions 30 of the memory pins and the outer diameterof theannular stops 32. Adjacent the solenoid 23 and in the area of at leasttwo and advantageously as many as six pin spaces, the holding plate 27is provided with a predetermined reset or erase portion 48 and aprogramming portion 58 having a substantially reduced diameter toaccommodate resetting and subsequent reprojection or programming of thepins 19 at the termination of one cycle and the commencement of the nextcycle of the memory wheel, as will be explained in more detailhereinafter. Supported in cantilever fashion from the reset portion 48of the holding plate and terminating at the programming portion 58, isan arcuate retraction cam 33 having a leading edge 34 which graduallyslopes downward in the direction of memory wheel rotation from theprojected height of the pins to the retracted height of the pins.

In accordance with the invention, L-shaped switch arms 35, 36 supportand maintain spray switches 20, 21, respectively, at a predeterminedadjustable distance from the solenoid 23 which corresponds to thedistance between the spray guns 14, 15, respectively, and the detectionswitch 22. The switches 20, 21 are limit switches having rolleractuators 37, 38, which are displaceable momentarily by the actuatingportions 29 of the projected memory pins, to initiate a predeterminedtime spraying sequence. The spray switch arms 35, 36 are adjustablyrotatable on the shaft 26 to any radial position corresponding to thelocation of a spray gun and are securable in that position by means ofset screws 39.

A spray timing sequence for the spray guns 14, 15

is preset in accordance with the size of the article being coated andthe speed of the conveyor 11 to limit the duration of spraying. Assumingeach spray gun has a predetermined limited range concentrated in thearea of its nozzle at a predetermined distance from the detection switch22, it is an advantageous aspect of the invention to be able to startthe spray only when the article has come within this specific range andnot sooner, and to terminate the spray when the article leaves the sprayrange. This conserves spray material, reduces contamination and, in thecase of electrostatic spraying, controls wrap-around with desiredprecision. To this end, a time delay mechanism 50-41, 501) for eachspray gun is preset to delay the spray starting signal from the sprayswitches 20, 21 for a preset time period (T in FIG. 5) which isequivalent to the time required for the conveyor to move the leadingedge 51 of an article 8 from a fixed center point at the edge of thespray chamber or spray zone into the range of the nozzle. At theexpiration of their delay intervals, the respective delay timers actuatespray timers 52a, 52b which start and maintain the sprays for intervals(T of sufiicient duration to allow the trailing edge 53 of the articleto have passed through the spray range.

Where parts are very closely spaced, the spray timers 52 may be set fora period long enough to spray a designated article and at least a partof the next successive article. In such a case, the spray timers will bereset to start before fully timing out, and the spray guns will remainin uninterrupted operation.

For unusually long parts, such as article 68 shown in FIG. 7, whichextend over a plurality of pendants, pairs fo hangers 13, 13a may beemployed. As will be understood, in this type of case the spray period Textends beyond the time required for a single predetermined increment ofadvance of the conveyor, and certain modifications will be appropriate.For example, to prevent the delay timer from being actuated by a memorypin projected by the trailing hanger 13a, the delay mechanism 50 may beappropriately set to be inoperative whenever the spray timer 52 isrunning, i.e., when the period T has not elapsed. Alternatively,specially configured trailing hangers might be employed, which trailinghangers would not actuate the detection switch 22 and, therefore, wouldnot cause the projection of more than one memory-pin for each article onthe conveyor.

Operation of the spray coating apparatus is as follows: The articles 8to be sprayed are placed on hangers 13 which are in turn, loaded ontothe conveyor pendants 12 at a remote loading station 60 (FIG. 1). As isto be understood, it is not necessary that an article be suspended fromeach pendant 12, since the memory wheel of the invention will change itsprogram of projected memory pins in accordance with the specific arrayof articles at any particular time as the conveyor traverses the spraybooth.

More specifically, as a hanger 13 passes and actuates the detectionswitch 22, indicating the presence of an article, the solenoid 23 willproject, in the area of the programming portion 58 of the plate 27, apin 19 into the position shown in FIG. 4. When the memory wheel is nextindexed by the regular actuation of the indexing switch 63 by regularlyspaced pendants 12, the inner surface 32b of the shoulder stop 32 of thepin will be engaged by the holding portions 28 of the plate 27 tomaintain the pin in its projected position as the wheel isintermittently rotated by the indexing drive 18. Upon the subsequentindexing of the memory wheel, the projected pin will reach the sprayswitches 20, 21 at the same time the article approaches the spray guns14, 15, due to the generally synchronous travel of the conveyor and thememory wheel and the proportional spacing of the detection switch andthe solenoid with relation to the spray guns and spray switches,respectively. The projected pins will then initiate the timers 50, 52 tocause the actuation of the spray.

After the spray treatment, the article will be conveyed forward, througha drying oven 53, before it is finally removed from the conveyor at theunloading station 61. During this time, the projected pin representingthat article is indexed about the holding portions 28 of the holdingplate until it reaches the reset portion 48 where it will engage the cam33. Continued indexing of the wheel will allow the pin to be cammed orreset into its inactive position (bottom of FIG. 3) at the end of itscycle. During the following cycle, the pin may be reprojected by thesolenoid 23 at the programming portion 48, as explained, or it may notbe projected by the solenoid in the absence of an article, in which casethe unprojected or inactive pin will be limited to that position by thecooperation of the outer surface 32a of the shoulder 32 with the holdingportion 28.

The coordinated stepwise movement of the memory Wheel with the conveyortravel will assure positive and sensitive actuation of the sprayswitches in accordance with the presence or absence of an article on theconveyor to effect a reliable, conveyor-actuated control of the sprayguns. Moreover, and as an important aspect of the invention, the sprayguns will be operated only in the immediate presence of articles to betreated and not during voids or gaps created by the specific spacings orsizes of the articles. As will readily be appreciated, the new andimproved spray programmer may effectively and economically beincorporated with conventional conveyorized spray apparatus to automateits control with relative ease and great realibility. In this respect,the capacity of the programming system is independent of the capacity ofthe conveyor system, as long as there are at least as many memory pinsas there are conveyor pendants in the space between the detectionstation and the spray station.

It should be understood that the specific form of the invention hereinillustrated and described is intended to be representative only, ascertain changes may be made therein without departing from the clearteachings of the disclosure. According, reference should be made to thefollowing appended claim in determining the full scope of the invention.

I claim:

An automatic control for a conveyorized spray treatment apparatuscomprising (a) a closed conveyor system including spaced suspensionmeans for engaging articles to be sprayed;

(b) means to drive the conveyor system at a predetermined rate;

(0) a mechanical memory unit analogically representative of at least aportion of the conveyor system and including a plurality of individualcontrol elements;

(d) means to drive the memory unit in accordance with movements of theconveyor system;

(e) spray means associated with the conveyor system and located remotelyof said memory unit, said spray means having a predetermined sprayrange;

(f) means for detecting suspended articles located adjacent the conveyorsystem and remotely of the spray means;

(g) said individual control elements on the control unit beinganalogically representative of a different points on the conveyor systemand being individually actuable between active and inactive positions;

(h) means for selectively positioning said control elements in activepositions in response to the sensing of suspended articles by saiddetection means;

(i) starting means associated with said control unit and actuatable bycontrol elements in active positions;

(1) a first controllable timer means actuatable by said starting meansand operable to actuate said spray mean-s after a first predeterminedelapse of time sufficient to accommodate the conveyance of an article tobe sprayed into said spray range; and

(k) a second controllable timer means actuatable by said first timer andoperable to deactuate said spray means after a second predeterminedelapse of time suificient to accommodate the traverse of said sprayrange by said article to be sprayed.

References Cited UNITED STATES PATENTS 2,369,155 2/1945 Marinsky et al.188-416 X 2,547,884 4/ 1951 Paasche 1182 2,906,214 9/1959 Frank 118-8 X2,961,990 11/1960 Wruck 1188 X 2,971,492 2/ 1961 Enssle 1182 3,013,44512/1961 Enssle 1182 X CHARLES A. WILLMUTH, Primary Examiner. J. P.MCINTOSH, Assistant Examiner.

